[BLDG-SIM] Fraction of Possible Sunshine

[cbarnaby@xxxxxxxxxxxxxx (Chip Barnaby)]

Jon --

I don't know of a source for a map, but I do have a question ... what do
you want it for?

I am trying to learn how people use this statistic.  It has been
traditionally observed, so people keep observing it.  I am involved
in work on ASHRAE TC 4.2 (Weather Information) that is developing methods
for extracting solar radiation from weather data measured by ASOS
(Automated Surface Observation System) now used to observe weather at
most sites in the US.  ASOS has planned to add sunshine meters to
their machines (that plan is now delayed due to funding), but it would be
just about as easy, and much more useful (in our opinion) to measure
solar radiation.  Sunshine fraction is a notoriously bad predictor
of solar radiation (the correlations are pretty poor).  With trivial
data processing, minute-by-minute solar radiation data can be used to
estimate sunshine, but not vice-versa.

Thus as far as I know the solar and building simulation community has no
use for sunshine data -- the statistic should be declared obsolete from
our point of view.  However, at every opportunity, I try to find why
people want it, there may be some other uses that we don't know
about.

So, if you're willing, please let me know what you're up to.

To the rest of BLDG-SIM: anyone else know of uses for sunshine
fraction?

Thanks, Chip Barnaby

> Does
> anyone out there have or know of a source for a graphical illustration of
> Fraction of Possible Sunshine over the U.S.  I found a very good
> table of such data at
> http://cdiac.esd.ornl.gov/ftp/ndp021/
> (file #12), but haven't had any luck with a map.  Thanks in advance.
>  
> Jon Maxwell, PE
> Aspen Systems Corp.
> jmaxwell@xxxxxxxxxxxx 
>  
>  
>
>
>
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---------------------------------------------------------
Chip Barnaby                   cbarnaby@xxxxxxxxxxxxxx
Vice President of Research
Wrightsoft Corp.               781-862-8719 x118 voice
394 Lowell St, Suite 12        781-861-2058 fax
Lexington, MA 02420            www.wrightsoft.com
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